import java.util.Arrays;
import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int n=scan.nextInt();
        int[] arr=new int[n];
        for(int i=0;i<n;i++)
        {
            arr[i]= scan.nextInt();
        }
        Arrays.sort(arr);
        int flag=1;
        for(int i=0;i<n-1;i++)
        {
            if((arr[i]^arr[i+1])==0)
            {
                System.out.println("YES");
                flag=0;
                break;
            }
        }
        if(flag==1)
            System.out.println("NO");
    }
}
